Contributors JS, the corresponding author, had full access to the data used in this study and had final responsibility for the decision
to submit for publication. JS and SM screened all retrieved references and reviewed papers meeting the inclusion criteria.
JS, SM, IS, MS, GH and RR collaborated on drafting the inclusion criteria and reviewed the list of included references. JS
and RR drafted the paper. All authors contributed to drafts of the paper and approved the final version.

Accepted 30 June 2012

Published Online First 11 October 2012

Abstract

Background England has invested in chlamydia screening interventions for young people. It is not known whether young people in poorer
socioeconomic circumstances (SEC) are at greater risk of chlamydia and therefore in greater need of screening.

Objective To conduct a systematic review examining socioeconomic variations in chlamydia prevalence or positivity in young people.

Eligibility Studies published 1999–2011 in North America, Western Europe, Australia or New Zealand, including populations aged 15–24 years,
with chlamydia prevalence or positivity diagnosed by nucleic acid amplification testing.

Appraisal and synthesis Two reviewers independently screened references, extracted data, appraised studies meeting inclusion criteria and rated studies
as high, medium or low according to their quality and relevance. Socioeconomic variations in chlamydia were synthesised for
medium/high-rated studies only.

Results No high-rated studies were identified. Eight medium-rated studies reported variations in chlamydia prevalence by SEC. In
6/8 studies, prevalence was higher in people of poorer SEC. Associations were more often significant when measured by education
than when using other indicators. All studies measuring positivity were rated low. Across all studies, methodological limitations
in SEC measurement were identified.

Conclusions The current literature is limited in its capacity to describe associations between SEC and chlamydia risk. The choice of
SEC measure may explain why some studies find higher chlamydia prevalence in young people in disadvantaged circumstances while
others do not. Studies using appropriate SEC indicators (eg, education) are needed to inform decisions about targeting chlamydia
screening.